Dead Ball?

[Tom Cook]

Last night in an 8th grade boys blowout. A1 is dribbling up the side and is pushed from the side by B1. I called the foul, but after the first foul and right at my whistle, A2 set an illegal screen on B1. The coach objected, naturally, and I told him that the ball was dead on the first foul. Therefore, there couldn't be another common foul on that play. Was I rignt, or is the ball live until the whistle? There was no shot involved.